bump required R version 3.5.0 -> 4.1.0

[cjyetman]

Since templates in https://github.com/RMI-PACTA/templates.transition.monitor, which are rather critical to this repo's function, use the new native R pipe |>, which was introduced in R v4.1.0, seems safest to make it a requirement for this package.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.80%. Comparing base (5f002dc) to head (eed866a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #101   +/-   ##
=====================================
  Coverage   0.80%   0.80%           
=====================================
  Files         25      25           
  Lines       1619    1619           
=====================================
  Hits          13      13           
  Misses      1606    1606           

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